mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-06-06 06:03:23 +00:00
Code Activity

Tree fix (#4864)

Browse source 
* simplify cheap equality tree

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

* simplify cheap equality tree

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

* more fixes

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2020-12-06 11:18:27 -08:00 • committed by GitHub
parent 0c93c7ae03
commit 2e5eb2dde2
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 147 additions and 149 deletions
Download patch file Download diff file Expand all files Collapse all files

288
src/math/lp/lp_bound_propagator.h
View file

@ -6,53 +6,73 @@
*/ */
#pragma once #pragma once
#include "math/lp/lp_settings.h" #include "math/lp/lp_settings.h"
#include <utility>
namespace lp { namespace lp {
template <typename T> template <typename T>
class lp_bound_propagator { class lp_bound_propagator {
// vertex represents a pair (row,x) or (row,y) for an offset row. class edge; // forward definition
// The set of all pair are organised in a tree. // vertex represents a column
// The edges of the tree are of the form ((row,x), (row, y)) for an offset row, // The set of vertices is organised in a tree.
// or ((row, u), (other_row, v)) where the "other_row" is an offset row too, // The edges of the tree are rows,
// and u, v reference the same column.
// Vertices with m_neg set to false grow with the same rate as the root. // Vertices with m_neg set to false grow with the same rate as the root.
// Vertices with m_neq set to true diminish with the same rate as the roow grows. // Vertices with m_neq set to true diminish with the same rate as the roow grows.
// When two vertices with the same m_neg have the same value of columns // When two vertices with the same m_neg have the same value of columns
// then we have an equality betweet the columns. // then we have an equality betweet the columns.
class vertex { class vertex {
unsigned m_row;
unsigned m_column; unsigned m_column;
ptr_vector<vertex> m_children; vector<edge> m_edges;
vertex* m_parent; edge m_edge_from_parent;
unsigned m_level; // the distance in hops to the root; unsigned m_level; // the distance in hops to the root;
// it is handy to find the common ancestor // it is handy to find the common ancestor
public: public:
vertex() {} vertex() {}
vertex(unsigned row, vertex(unsigned column) :
unsigned column) :
m_row(row),
m_column(column), m_column(column),
m_parent(nullptr),
m_level(0) m_level(0)
{} {}
unsigned column() const { return m_column; } unsigned column() const { return m_column; }
unsigned row() const { return m_row; } const vertex* parent() const { return m_edge_from_parent.source(); }
vertex* parent() const { return m_parent; } vertex* parent() { return m_edge_from_parent.source(); }
unsigned level() const { return m_level; } unsigned level() const { return m_level; }
void add_child(vertex* child) { void set_edge_from_parent(edge &e) { m_edge_from_parent = e; }
SASSERT(!(*this == *child)); const edge& edge_from_parent() const { return m_edge_from_parent; }
child->m_parent = this;
m_children.push_back(child); void add_child(int row, vertex* child) {
SASSERT(*this != *child);
SASSERT(child->parent() == nullptr);
edge e = edge(this, child, row);
m_edges.push_back(e);
child->set_edge_from_parent(e);
child->m_level = m_level + 1; child->m_level = m_level + 1;
} }
const ptr_vector<vertex> & children() const { return m_children; } const vector<edge> & edges() const { return m_edges; }
bool operator==(const vertex& o) const { bool operator==(const vertex& o) const {
return m_row == o.m_row && m_column == o.m_column; return m_column == o.m_column;
}
bool operator!=(const vertex& o) const {
return m_column != o.m_column;
} }
}; };
class edge {
vertex* m_source;
vertex* m_target;
int m_row;
public:
edge(vertex* source, vertex* target, int row) : m_source(source), m_target(target), m_row(row) {}
edge() : m_source(nullptr), m_target(nullptr), m_row(-1) {}
const vertex* source() const { return m_source; }
vertex* source() { return m_source; }
const vertex* target() const { return m_target; }
vertex* target() { return m_target; }
int row() const { return m_row; }
edge reverse() const { return edge(m_target, m_source, m_row); }
};
static int other(int x, int y, int z) { SASSERT(x == z || y == z); return x == z ? y : x; }
std::ostream& print(std::ostream & out, const vertex* v) const { std::ostream& print(std::ostream & out, const vertex* v) const {
out << "r = " << v->row() << ", c = " << v->column() << ", P = {"; out << "c = " << v->column() << ", P = {";
if (v->parent()) { out << "(" << v->parent()->row() << ", " << v->parent()->column() << ")";} if (v->parent()) { out << "(" << v->parent()->column() << ")";}
else { out << "null"; } else { out << "null"; }
out << "} , lvl = " << v->level(); out << "} , lvl = " << v->level();
if (fixed_phase()) { if (fixed_phase()) {
@ -67,6 +87,7 @@ class lp_bound_propagator {
hashtable<unsigned, u_hash, u_eq> m_visited_rows; hashtable<unsigned, u_hash, u_eq> m_visited_rows;
hashtable<unsigned, u_hash, u_eq> m_visited_columns; hashtable<unsigned, u_hash, u_eq> m_visited_columns;
u_map<vertex*> m_vertices;
vertex* m_root; vertex* m_root;
// At some point we can find a row with a single vertex non fixed vertex // At some point we can find a row with a single vertex non fixed vertex
// then we can fix the whole tree, // then we can fix the whole tree,
@ -195,7 +216,7 @@ public:
return; return;
TRACE("cheap_eq", tout << "found j=" << j << " for v="; TRACE("cheap_eq", tout << "found j=" << j << " for v=";
print(tout, v) << "\n in lp.fixed tables\n";); print(tout, v) << "\n in lp.fixed tables\n";);
ptr_vector<const vertex> path; vector<edge> path;
find_path_on_tree(path, v, m_fixed_vertex); find_path_on_tree(path, v, m_fixed_vertex);
explanation ex = get_explanation_from_path(path); explanation ex = get_explanation_from_path(path);
ex.add_expl(m_fixed_vertex_explanation); ex.add_expl(m_fixed_vertex_explanation);
@ -216,7 +237,7 @@ public:
TRACE("cheap_eq", tout << "found j=" << j << " for v="; TRACE("cheap_eq", tout << "found j=" << j << " for v=";
print(tout, v) << "\n in m_vals_to_verts\n";); print(tout, v) << "\n in m_vals_to_verts\n";);
ptr_vector<const vertex> path; vector<edge> path;
find_path_on_tree(path, u, v); find_path_on_tree(path, u, v);
explanation ex = get_explanation_from_path(path); explanation ex = get_explanation_from_path(path);
ex.add_expl(m_fixed_vertex_explanation); ex.add_expl(m_fixed_vertex_explanation);
@ -227,8 +248,8 @@ public:
bool tree_contains_r(vertex* root, vertex *v) const { bool tree_contains_r(vertex* root, vertex *v) const {
if (*root == *v) if (*root == *v)
return true; return true;
for (vertex *c : root->children()) { for (auto e : root->edges()) {
if (tree_contains_r(c, v)) if (tree_contains_r(e.target(), v))
return true; return true;
} }
return false; return false;
@ -244,7 +265,7 @@ public:
m_pol.insert(j, pol_vert(p, v)); m_pol.insert(j, pol_vert(p, v));
} }
void check_polarity(vertex* v, int polarity) { void check_and_set_polarity(vertex* v, int polarity, unsigned row_index) {
pol_vert prev_pol; pol_vert prev_pol;
if (!m_pol.find(v->column(), prev_pol)) { if (!m_pol.find(v->column(), prev_pol)) {
set_polarity(v, polarity); set_polarity(v, polarity);
@ -255,9 +276,10 @@ public:
const vertex *u = prev_pol.v(); const vertex *u = prev_pol.v();
// we have a path L between u and v with p(L) = -1, that means we can // we have a path L between u and v with p(L) = -1, that means we can
// create an equality of the form x + x = a, where x = v->column() = u->column() // create an equality of the form x + x = a, where x = v->column() = u->column()
ptr_vector<const vertex> path; vector<edge> path;
find_path_on_tree(path, u, v); find_path_on_tree(path, u, v);
m_fixed_vertex_explanation = get_explanation_from_path(path); m_fixed_vertex_explanation = get_explanation_from_path(path);
explain_fixed_in_row(row_index, m_fixed_vertex_explanation);
set_fixed_vertex(v); set_fixed_vertex(v);
TRACE("cheap_eq", tout << "polarity switch between: v = "; print(tout , v) << "\nand u = "; print(tout, u) << "\n";); TRACE("cheap_eq", tout << "polarity switch between: v = "; print(tout , v) << "\nand u = "; print(tout, u) << "\n";);
TRACE("cheap_eq", tout << "fixed vertex explanation\n"; TRACE("cheap_eq", tout << "fixed vertex explanation\n";
@ -273,8 +295,9 @@ public:
return tree_contains_r(m_root, v); return tree_contains_r(m_root, v);
} }
vertex * alloc_v(unsigned row_index, unsigned column) { vertex * alloc_v(unsigned column) {
vertex * v = alloc(vertex, row_index, column); vertex * v = alloc(vertex, column);
m_vertices.insert(column, v);
SASSERT(!tree_contains(v)); SASSERT(!tree_contains(v));
return v; return v;
} }
@ -286,24 +309,23 @@ public:
SASSERT(!m_root && !m_fixed_vertex); SASSERT(!m_root && !m_fixed_vertex);
unsigned x, y; unsigned x, y;
int polarity; int polarity;
TRACE("cheap_eq", print_row(tout, row_index);); TRACE("cheap_eq_det", print_row(tout, row_index););
if (!is_tree_offset_row(row_index, x, y, polarity)) { if (!is_tree_offset_row(row_index, x, y, polarity)) {
TRACE("cheap_eq", tout << "not an offset row\n";); TRACE("cheap_eq_det", tout << "not an offset row\n";);
return; return;
} }
const mpq& r = val(x); TRACE("cheap_eq", print_row(tout, row_index););
m_root = alloc_v(row_index, x); m_root = alloc_v(x);
set_polarity(m_root, 1); set_polarity(m_root, 1); // keep m_root in the positive table
if (not_set(y)) { if (not_set(y)) {
set_fixed_vertex(m_root); set_fixed_vertex(m_root);
explain_fixed_in_row(row_index, m_fixed_vertex_explanation); explain_fixed_in_row(row_index, m_fixed_vertex_explanation);
} else { } else {
vertex *v = alloc_v(row_index, y); vertex *v = add_child_with_check(row_index, y, m_root, polarity);
m_root->add_child(v); if (v)
set_polarity(v, polarity); explore_under(v);
} }
// keep root in the positive table explore_under(m_root);
m_vals_to_verts.insert(r, m_root);
} }
unsigned column(unsigned row, unsigned index) { unsigned column(unsigned row, unsigned index) {
@ -312,38 +334,44 @@ public:
bool fixed_phase() const { return m_fixed_vertex; } bool fixed_phase() const { return m_fixed_vertex; }
// Returns the vertex to start exploration from, or nullptr. // Returns the vertex to start exploration from, or nullptr.
// It is assumed that parent->column() is present in the row // It is assumed that parent->column() is present in the row
vertex* add_child_from_row(unsigned row_index, vertex* parent) { vertex* get_child_from_row(unsigned row_index, vertex* parent) {
TRACE("cheap_eq", print_row(tout, row_index);); TRACE("cheap_eq_det", print_row(tout, row_index););
unsigned x, y; int polarity; unsigned x, y; int row_polarity;
if (!is_tree_offset_row(row_index, x, y, polarity)) { if (!is_tree_offset_row(row_index, x, y, row_polarity)) {
TRACE("cheap_eq", tout << "not an offset row\n"; ); TRACE("cheap_eq_det", tout << "not an offset row\n"; );
return nullptr; return nullptr;
} }
if (not_set(y)) { if (not_set(y)) { // there is only one fixed variable in the row
SASSERT(parent->column() == x);
vertex *v = alloc_v(row_index, x);
parent->add_child(v);
if (!fixed_phase()) { if (!fixed_phase()) {
set_fixed_vertex(v); set_fixed_vertex(parent);
explain_fixed_in_row(row_index, m_fixed_vertex_explanation); explain_fixed_in_row(row_index, m_fixed_vertex_explanation);
} }
return v; return nullptr;
} }
SASSERT(is_set(x) && is_set(y)); SASSERT(is_set(x) && is_set(y));
unsigned col = other(x, y, parent->column());
return add_child_with_check(row_index, col, parent, row_polarity);
}
// v has the column of the parent, but the row is different vertex * add_child_with_check(unsigned row_index, unsigned col, vertex* parent, int row_polarity) {
vertex *v = alloc_v(row_index, parent->column()); vertex* vy;
parent->add_child(v); if (m_vertices.find(col, vy)) {
SASSERT(x == v->column() || y == v->column()); SASSERT(vy != nullptr);
unsigned col = v->column() == y? x : y; if (!fixed_phase()) {
vertex *vy = alloc_v(v->row(), col); check_and_set_polarity(vy, pol(parent) * row_polarity, row_index);
v->add_child(vy); }
return nullptr; // it is not a new vertex
}
vy = alloc_v(col);
parent->add_child(row_index, vy);
if (!fixed_phase()) if (!fixed_phase())
check_polarity(vy, polarity * pol(v)); check_and_set_polarity(vy, row_polarity * pol(parent), row_index);
return v; return vy;
} }
bool is_equal(lpvar j, lpvar k) const { bool is_equal(lpvar j, lpvar k) const {
@ -384,30 +412,31 @@ public:
m_root = nullptr; m_root = nullptr;
} }
std::ostream& print_path(const ptr_vector<const vertex>& path, std::ostream& out) const { std::ostream& print_edge(const edge& e, std::ostream& out) const {
unsigned pr = UINT_MAX; out << e.source()->column() << "->" << e.target()->column() << "\n";
out << "path = \n"; return print_row(out, e.row());
for (const vertex* k : path) {
print(out, k) << "\n";
if (k->row() != pr) {
print_row(out, pr = k->row());
} }
std::ostream& print_path(const vector<edge>& path, std::ostream& out) const {
out << "path = \n";
for (const edge& k : path) {
print_edge(k, out) << "\n";
} }
return out; return out;
} }
// we have v_i and v_j, indices of vertices at the same offsets // we have v_i and v_j, indices of vertices at the same offsets
void report_eq(const vertex* v_i, const vertex* v_j) { void report_eq(const vertex* v_i, const vertex* v_j) {
SASSERT(v_i != v_j); SASSERT(v_i != v_j);
SASSERT(lp().get_column_value(v_i->column()) == lp().get_column_value(v_j->column())); SASSERT(lp().get_column_value(v_i->column()) == lp().get_column_value(v_j->column()));
TRACE("cheap_eq", tout << v_i->column() << " = " << v_j->column() << "\nu = "; TRACE("cheap_eq", tout << v_i->column() << " = " << v_j->column() << "\nu = ";
print(tout, v_i) << "\nv = "; print(tout, v_j) <<"\n"; print(tout, v_i) << "\nv = "; print(tout, v_j) <<"\n";
display_row_of_vertex(v_i, tout);
if (v_j->row() != v_i->row())
display_row_of_vertex(v_j, tout);
); );
ptr_vector<const vertex> path; vector<edge> path;
find_path_on_tree(path, v_i, v_j); find_path_on_tree(path, v_i, v_j);
lp::explanation exp = get_explanation_from_path(path); lp::explanation exp = get_explanation_from_path(path);
add_eq_on_columns(exp, v_i->column(), v_j->column()); add_eq_on_columns(exp, v_i->column(), v_j->column());
@ -443,27 +472,22 @@ public:
return lp().column_is_int(j); return lp().column_is_int(j);
} }
explanation get_explanation_from_path(const ptr_vector<const vertex>& path) const { explanation get_explanation_from_path(vector<edge>& path) const {
explanation ex; explanation ex;
unsigned prev_row = UINT_MAX; for (edge &e : path)
for (const vertex* k : path) { explain_fixed_in_row(e.row(), ex);
unsigned row = k->row();
if (row == prev_row)
continue;
explain_fixed_in_row(prev_row = row, ex);
}
return ex; return ex;
} }
void explain_fixed_in_row(unsigned row, explanation& ex) const { void explain_fixed_in_row(unsigned row, explanation& ex) const {
for (const auto & c : lp().get_row(row)) { for (const auto & c : lp().get_row(row)) {
if (lp().is_fixed(c.var())) { if (lp().is_fixed(c.var())) {
explain_fixed_column(ex, c.var()); explain_fixed_column(c.var(), ex);
} }
} }
} }
void explain_fixed_column(explanation & ex, unsigned j) const { void explain_fixed_column(unsigned j, explanation & ex) const {
SASSERT(column_is_fixed(j)); SASSERT(column_is_fixed(j));
constraint_index lc, uc; constraint_index lc, uc;
lp().get_bound_constraint_witnesses_for_column(j, lc, uc); lp().get_bound_constraint_witnesses_for_column(j, lc, uc);
@ -471,86 +495,58 @@ public:
ex.push_back(uc); ex.push_back(uc);
} }
std::ostream& display_row_of_vertex(const vertex* k, std::ostream& out) const { void find_path_on_tree(vector<edge> & path, const vertex* u, const vertex* v) const {
return print_row(out, k->row());
}
void find_path_on_tree(ptr_vector<const vertex> & path, const vertex* u, const vertex* v) const {
TRACE("cheap_eq_details", tout << "u = " ; print(tout, u); tout << "\nv = ";print(tout, v) << "\n";); TRACE("cheap_eq_details", tout << "u = " ; print(tout, u); tout << "\nv = ";print(tout, v) << "\n";);
vertex* up; // u parent vector<edge> v_branch;
vertex* vp; // v parent
vector<const vertex*> v_branch;
path.push_back(u);
v_branch.push_back(v);
// equalize the levels // equalize the levels
while (u->level() > v->level()) { while (u->level() > v->level()) {
up = u->parent(); path.push_back(u->edge_from_parent().reverse());
if (u->row() == up->row()) u = u->parent();
path.push_back(up);
u = up;
} }
while (u->level() < v->level()) { while (u->level() < v->level()) {
vp = v->parent(); v_branch.push_back(v->edge_from_parent());
if (v->row() == vp->row()) v = v->parent();
v_branch.push_back(vp);
v = vp;
} }
SASSERT(u->level() == v->level()); SASSERT(u->level() == v->level());
TRACE("cheap_eq_details", tout << "u = " ; print(tout, u); tout << "\nv = "; print(tout, v) << "\n";); TRACE("cheap_eq_details", tout << "u = " ; print(tout, u); tout << "\nv = "; print(tout, v) << "\n";);
while (u != v) { while (u != v) {
up = u->parent(); path.push_back(u->edge_from_parent().reverse());
vp = v->parent(); v_branch.push_back(v->edge_from_parent());
if (up->row() == u->row()) u = u->parent();
path.push_back(up); v = v->parent();
if (vp->row() == v->row())
v_branch.push_back(vp);
u = up; v = vp;
} }
for (unsigned i = v_branch.size(); i--; ) { for (unsigned i = v_branch.size(); i--; ) {
const vertex * bv = v_branch[i]; path.push_back(v_branch[i]);
if (path.back() != bv)
path.push_back(bv);
} }
TRACE("cheap_eq", print_path(path, tout);); TRACE("cheap_eq", print_path(path, tout););
} }
bool tree_is_correct() const { bool tree_is_correct() const {
ptr_vector<vertex> vs; std::unordered_set<int> vs;
vs.push_back(m_root);
return tree_is_correct(m_root, vs); return tree_is_correct(m_root, vs);
} }
bool contains_vertex(vertex* v, const ptr_vector<vertex> & vs) const {
for (auto* u : vs) { bool tree_is_correct(vertex* v, std::unordered_set<int>& visited_verts) const {
if (*u == *v)
return true;
}
return false;
}
bool tree_is_correct(vertex* v, ptr_vector<vertex>& vs) const {
if (fixed_phase()) if (fixed_phase())
return true; return true;
for (vertex * u : v->children()) { if (visited_verts.find(v->column()) != visited_verts.end())
if (contains_vertex(u, vs)) return false;
visited_verts.insert(v->column());
for (auto e : v->edges()) {
if (!tree_is_correct(e.target(), visited_verts))
return false; return false;
} }
for (vertex * u : v->children()) {
vs.push_back(u);
}
for (vertex * u : v->children()) {
if (!tree_is_correct(u, vs))
return false;
}
return true; return true;
} }
std::ostream& print_tree(std::ostream & out, vertex* v) const { std::ostream& print_tree(std::ostream & out, vertex* v) const {
print(out, v); print(out, v);
out << "\nchildren :\n"; out << "\nchildren :\n";
for (auto * c : v->children()) { for (auto c : v->edges()) {
print_tree(out, c); out << "row = ";
print_row(out, c.row());
print_tree(out, c.target());
} }
return out; return out;
} }
@ -562,8 +558,8 @@ public:
void create_fixed_eqs(const vertex* v) { void create_fixed_eqs(const vertex* v) {
try_add_equation_with_fixed_tables(v); try_add_equation_with_fixed_tables(v);
for (vertex* c: v->children()) for (auto e: v->edges())
try_add_equation_with_fixed_tables(c); try_add_equation_with_fixed_tables(e.target());
} }
void handle_fixed_phase() { void handle_fixed_phase() {
@ -571,7 +567,7 @@ public:
} }
void cheap_eq_tree(unsigned row_index) { void cheap_eq_tree(unsigned row_index) {
TRACE("cheap_eq", tout << "row_index = " << row_index << "\n";); TRACE("cheap_eq_det", tout << "row_index = " << row_index << "\n";);
if (!check_insert(m_visited_rows, row_index)) if (!check_insert(m_visited_rows, row_index))
return; // already explored return; // already explored
create_root(row_index); create_root(row_index);
@ -580,7 +576,6 @@ public:
} }
TRACE("cheap_eq", tout << "tree = "; print_tree(tout, m_root) << "\n";); TRACE("cheap_eq", tout << "tree = "; print_tree(tout, m_root) << "\n";);
SASSERT(tree_is_correct()); SASSERT(tree_is_correct());
explore_under(m_root);
if (fixed_phase()) if (fixed_phase())
handle_fixed_phase(); handle_fixed_phase();
TRACE("cheap_eq", tout << "done for row_index " << row_index << "\n";); TRACE("cheap_eq", tout << "done for row_index " << row_index << "\n";);
@ -592,6 +587,7 @@ public:
m_vals_to_verts.reset(); m_vals_to_verts.reset();
m_vals_to_verts_neg.reset(); m_vals_to_verts_neg.reset();
m_pol.reset(); m_pol.reset();
m_vertices.reset();
} }
std::ostream& print_row(std::ostream & out, unsigned row_index) const { std::ostream& print_row(std::ostream & out, unsigned row_index) const {
@ -628,14 +624,14 @@ public:
unsigned subtree_size(vertex* v) const { unsigned subtree_size(vertex* v) const {
unsigned r = 1; // 1 for v unsigned r = 1; // 1 for v
for (vertex * u : v->children()) for (auto e : v->edges())
r += subtree_size(u); r += subtree_size(e.target());
return r; return r;
} }
void delete_tree(vertex * v) { void delete_tree(vertex * v) {
for (vertex* u : v->children()) for (auto p : v->edges())
delete_tree(u); delete_tree(p.target());
dealloc(v); dealloc(v);
} }
@ -656,8 +652,14 @@ public:
unsigned row_index = c.var(); unsigned row_index = c.var();
if (!check_insert(m_visited_rows, row_index)) if (!check_insert(m_visited_rows, row_index))
continue; continue;
vertex *u = add_child_from_row(row_index, v); vertex *u = get_child_from_row(row_index, v);
if (u) { if (u) {
// debug
// if (verts_size() > 3) {
// std::cout << "big tree\n";
// TRACE("cheap_eq", print_tree(tout, m_root););
// exit(1);
// } // end debug
explore_under(u); explore_under(u);
} }
} }
@ -666,10 +668,6 @@ public:
void explore_under(vertex * v) { void explore_under(vertex * v) {
check_for_eq_and_add_to_val_tables(v); check_for_eq_and_add_to_val_tables(v);
go_over_vertex_column(v); go_over_vertex_column(v);
// v might change in m_vertices expansion
for (vertex* c : v->children()) {
explore_under(c);
}
} }
// In case of only one non fixed column, and the function returns true, // In case of only one non fixed column, and the function returns true,